Health Information

Jellyfish Stings

Playing in the ocean is a summertime tradition, but a jellyfish sting can spoil the fun. Here's how to handle it if someone in your family gets zapped by one of these mysterious sea creatures.

What Are Jellyfish Stings?

Jellyfish have been around for millions of years and live in oceans all over the world. There are many different types of jellyfish. Some just look like small, clear blobs, while others are bigger and more colorful with tentacles hanging beneath them.

It's the tentacles that sting. Jellyfish sting their prey with them, releasing a venom that paralyzes their targets. Jellyfish don't go after humans, but someone who swims up against or touches one — or even steps on a dead one — can be stung all the same.

While jellyfish stings are painful, most are not emergencies. Expect pain, red marks, itching, numbness, or tingling with a typical sting.

But stings from some types of jellyfish — such as the box jellyfish (also called sea wasp) — are very dangerous, and can even be deadly. These jellyfish are most often found in Australia, the Philippines, the Indian Ocean, and central Pacific Ocean.

How Are Jellyfish Stings Treated?

Jellyfish stings leave thousands of very tiny stingers called nematocysts in the skin. These stingers can continue to release (or "fire") jellyfish venom (poison) into the body.

It's best to rinse a sting with vinegar. Vinegar is a weak acid that might keep the stingers from firing for some kinds of stings (especially from dangerous types like box jellyfish). Rinsing with cool fresh water can make more stingers fire. Also, rinsing a sting with seawater had been thought to prevent them from releasing more venom. But now, some experts say that can actually make a sting worse.

Also, do not scrape off any stingers still in the skin. This also used to be recommended, but now is thought to make stings worse.

To deal with a sting:

Remove your child from the water.

Rinse the area with vinegar. (Keep a small plastic bottle of vinegar in your beach bag, just in case.)

Don't rub the area, which can make things worse.

Use tweezers to pluck away any tentacles still on the skin. Do not scrape the area with a credit card or other stiff card.

Do not apply ice or ice packs to a sting. A hot (but not scalding) shower or soak may help lessen pain.

Check in with your health care professional to see if pain relievers might help your child feel better.

Call an ambulance immediately if someone has been stung and:

is having trouble breathing or swallowing

has a swollen tongue or lips, or a change in voice

has bad pain or feels generally unwell

is nauseated or vomiting

is dizzy or has a headache

has muscle spasms

has stings over a large part of the body

the sting is in the eye or mouth

may have been stung by a very dangerous jellyfish

Can Jellyfish Stings Be Prevented?

Guarded beaches are more likely to warn visitors about jellyfish. Look for a sign or warning flag (some beaches fly a purple warning flag when there's "dangerous marine life" in the water). Double check to make sure that you've got a small container of vinegar and a pair of tweezers in your beach bag.